1 Answer
1

Your man command is using groff to format the page with ANSI color
escape sequences (ISO 6429), and your pagination program (likely more
or less) is expanding these unprintable characters instead of passing
them unchanged to your terminal screen.

To tell less (for example) not to expand these ANSI sequences, use
the -R or --RAW-CONTROL-CHARS option. You can often do this by
setting the option you want in the LESS environment variable or
perhaps using the PAGER environment variable:

$ LESS='-R' man groff
$ PAGER='less -R' man groff

It might also be an incorrect directive to the underlying groff,
causing groff (or grotty) to issue ANSI escapes when you don't
really want them. You can tell man not to use the escapes by using
something like this:

$ man --ascii groff

The man page for grotty talks in detail about your options for fixing
the problem.